000 AXPZ20 KNHC 012118 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Oct 1 2017 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2100 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Panama and Costa Rica to 1007 mb low pres near 13N94W to 1008 mb low pres near 10N109W to 1008 mb low pres near 11N114W to 10N124W to beyond 09N140W. Scattered moderate convection is from 08N to 11N between 87W and 92W, from 10N to 12N between 113W and 115W, and from 10N to 12N between 128W and 132W. Scattered moderate isolated strong convection is 10N to 14N between 94W and 98W, and from 08N to 12N W of 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to locally strong gap winds will develop over the Gulf of Tehuantepec during the overnight and early morning hours through Tuesday as a ridge persists across the western Gulf of Mexico and the eastern slopes of the Sierra Madre Mountains. Seas will build to 6-7 ft through early Monday morning, and to 7-8 ft by early Tuesday morning. Marine guidance suggests increasing winds and building seas across the Tehuantepec area as an area of low pressure develops a few hundred miles south of the southern coast of Mexico or Guatemala in a couple of days. Environmental conditions are expected to be conducive for gradual development while the system moves slowly west-northwestward or northwestward. Elsewhere, a ridge dominates the waters west of the Baja California Peninsula producing gentle to moderate northerly winds and seas of 4 to 5 ft. Northerly swell are propagating into the waters west of Baja California Norte today, building seas to 8 to 9 ft, which are expected to last through Tuesday. Fresh to locally strong S-SW winds are expected over the northern Gulf of California tonight through Tuesday as low pressure develops over the area. Seas over the northern gulf will reach 6-7 ft during that time. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough is currently across Central America and adjacent waters with widespread convection. The trough will remain close enough to the coast, either inland or just offshore, to produce additional active convection over portions of Central America as well as the adjacent coastal waters during the next few days. As a result, locally heavy rain will be possible over higher terrain of portions of central America early this week. Winds and seas are expected to increase over the offshore forecast waters through the forecast period. Fresh to strong SW to W winds and seas of 8 to 11 ft are expected to affect the waters beyond 200 nm off the coast from Nicaragua to Guatemala beginning Monday morning through Thursday. Cross equatorial SW swell, with periods of 20 to 22 seconds are forecast to reach the waters between Ecuador and the Galapagos Islands Tuesday night, building seas to 7-8 ft by Wednesday night. REMAINDER OF THE AREA... High pressure of 1027 mb centered N of the area near 36N134W extends across the waters N of 20N. The pressure gradient between the ridge and the monsoon trough is supporting moderate to locally fresh NE winds roughly from 15N to 25N W of 130W based on scattermeter data. The high pressure is forecast to move SW over the next 24 hours, reaching a position near 35N138W. The pressure gradient between the high and lower pressure inland over the SW of U.S., and NW Mexico will produce N winds of 20-25 kt across the waters N of 28N between 122W and 130W by Monday afternoon. These winds combined with northerly swell propagating into the waters north of 24N between 120W and 130W through Tuesday will build seas to near 12 ft along 30N by Monday morning. Farther south, cross equatorial southerly swell will propagate across the waters south of 02N between 105W and 135W by Tuesday, with seas building to 8-10 ft. $$ GR